In this paper, we study the periodic solutions bifurcating from a nonisolated zero-Hopf equilib- rium in a polynomial differential system of degree two in R³. More specifically, we use recent results of averaging theory to improve the conditions for the existence of one or two periodic solutions bifurcating from such a zero-Hopf equilibrium. This new result is applied for studying the periodic solutions of differential systems in R³ having n-scroll chaotic attractors.